1. Field of the Invention
The present invention relates to an image processing apparatus for detecting a specific image for which printing is not permitted.
2. Related Background Art
Recently, because of the phenomenal development and spread of computers and computer networks, various types of data, including character data, image data and speech data, have been or are being digitized. While the use of digital data is preferable, because it does not deteriorate with the passage of time and thus maintains its initial integrity, copying digital data is such a simple, commonly employed practice that the protection of copyrighted material has become a huge problem. Therefore, the availability of security techniques that can be used to protect copyrights is immensely important today.
One means of providing copyright protection is through the application of a technique called “electronic watermarking”. Electronic watermarking is a technique whereby the name of a copyright holder and the ID of a purchaser can be embedded in digital image, speech, or character data. Since a form is used that is not discernable by a human being, this technique can be used to track the unauthorized copying and use of digital data.
Further, the electronic watermarking technique can be employed not only to track the unauthorized use of data through illegal copying, but can also be used to detect the illegal printing of specific images, such as paper currencies or securities. For according to this technique, an electronic watermark can be embedded in advance in a specific image, and at the time of printing, the specific image can be detected by extracting the electronic watermark.
A conventional electronic watermark extraction apparatus performs the same process for all received images, regardless of whether electronic watermarks have previously been embedded in them. Since the extraction apparatus performs unnecessary processing for images in which no electronic watermarks have been embedded, the time required to extract an electronic watermark is extended.
In addition, when a specific image in which an electronic watermark has been embedded is to be detected at the time of printing, a conventional electronic watermark extraction apparatus performs an unnecessary process for most images that have not been so specified, and this extends the printing time.